As technology continues to progress and develop, various electronic devices such as flash drives, mobile phones, MP3, etc. are constantly being introduced, which not only allows users to fully enjoy the fruits of scientific and technological progress, but also significantly enhances work efficiency. Among the electronic devices, flash drives have the advantages of large capacity, fast transmission speed, portable, low cost, convenience and plug to use. Flash drives are widely used in data transmission, however, because the size of the flash drive is usually small and may be lost when carrying it. Also, when the user carries the flash drive, the connecting portion of the flash drive may suffer from collision or abrasion. Furthermore, when the weather or the temperature of the user changes, the flash drive is easy to be moisturized to cause short circuit and reduce the durability thereof. Moreover, the style or design of the flash drive may affect the desire of people to purchase and carry the flash drive, so the flash drive with monotonous design is less desirable and unattractive, and difficult to increase additional value of the flash drive. When considering the life of the flash drive, if the user is tired of the style or design of the flash drive, the user is not able to change the appearance of the flash drive. Thus, there remains a need for a new and improved cover for the flash drive to overcome the problems above.